1. Field of the Invention
The present invention relates to improvements in the control of transfer of material to a working tank in a ceramic molding machine.
2. Prior Art
Continuous ceramic molding machines have been advanced, and a typical machine of the type with which the present invention would be used in shown in USSR Pat. No. 159,127. In this particular patent, a molding machine is illustrated, including a multi-cavity mold which is fed from a working tank containing a ceramic slurry in an automatic process. The machine further includes a preparation tank where the solid ceramic material is preheated and mixed to form a slurry and vacuum treated. The slurry is subsequently transferred to the working tank, which also is heated has a mixer and vacuum.
In the machine described in the above identified USSR Patent, the level of slurry in the working tank was controlled through the use of a float valve. The conduit which transferred the slurry from the preparation tank to the working tank formed a passageway which permitted the slurry to flow to the working tank when vacuum was applied to the top of the working tank. When the level of the slurry in the working tank reached a predetermined height, the float valve provided a signal which caused water to cool a section of the conduit between the tanks to a level where the ceramic material in the conduit would solidify, and prevent further transfer from the preparation tank to the working tank. The floats for the valves were causing constant problems because the ceramic material in the slurry would tend to solidify on the float changing its bouyancy and therefore requiring periodic removal and cleaning.
Other types of level controls have been tried, such as X-Ray detectors, which proved to present some hazards to personnel, and photosensitive sensors, which failed to function when the ceramic slurry would solidify over the receptors or senders, and block the light.
Additionally, a second USSR Pat. No. 155,426 illustrates schematically the same type of a molding machine with which the present device is used, showing a preparation tank and a working tank, and relates in particular to valves which can be utilized for controlling fluids to effect transfer of material from the working tank to the mold and from the preparation tank to the working tank.